Occlusion Device and Method for its Manufacture

ABSTRACT

The present invention relates to an occlusion device ( 1 ) consisting of a braiding ( 2 ) of thin wires or threads ( 4 ) which is given a suitable form in a molding and heat treatment procedure. The occlusion device ( 1 ) has a proximal retention area ( 6 ) and a distal retention area ( 8 ), whereby the ends of the wires or threads ( 4 ) converge into a holder ( 5 ) in distal retention area ( 8 ). A cylindrical crosspiece ( 10 ) is furthermore disposed between the proximal and distal retention areas ( 6, 8 ). With the objective of providing an occlusion device which positions as flat as possible against the septum at the proximal side of a septal defect in the inserted state, the invention provides for the proximal retention area ( 6 ) of the braiding ( 2 ) to exhibit a completely closed proximal wall ( 112 ) disposed with a continuous surface at the proximal end of the occlusion device ( 1 ) which forms the proximal end ( 12 ) of said occlusion device ( 1 ).

The present invention relates to an occlusion device consisting of aholder and a braiding of thin wires or threads given a suitable form bymeans of a molding and heat treatment procedure, whereby the occlusiondevice has a proximal retention area and a distal retention area,wherein the ends of the wires converge into a holder in the distalretention area, and a cylindrical crosspiece interposed between theproximal and distal retention areas, whereby the two retention areas arepositioned on the two sides of a shunt to be occluded in a septum,usually by way of an intravascular surgical procedure, while thecrosspiece transverses the shunt. The invention moreover relates to amethod for manufacturing said occlusion device.

Medical technology has long endeavored to be able to occlude septaldefects, for instance atrial septal defects, with non-surgicaltransvenous catheter intervention, in other words, without having toperform an operation in the literal sense. Various different occlusionsystems have been proposed, each with their own advantages anddisadvantages, without any one specific occlusion system having yetbecome widely accepted. In making reference to these different systems,the following will use the terms “occluder” or “occlusion device.”

In all interventional occlusion systems, a self-expanding umbrellasystem is introduced transvenously into a defect to be occluded in aseptum. This type of system might comprise two umbrellas; one positionedat the distal side of the septum, for example (i.e. the side farthestfrom the median plane of the body/heart), and one at the proximal sideof the septum (i.e. the side closer to the median plane of the body),whereby the two umbrella prostheses are subsequently fitted into adouble umbrella in the septal defect. Thus, in the assembled state, theocclusion system usually consists of two fixed umbrellas connected toone another by means of a short peg which passes through the defect.

However, a disadvantage to such known prior art occlusion devices turnsout to be the relatively complicated, difficult and complex implantationprocedure. Apart from the complicated implantation of the occlusionsystem in the septal defect to be occluded, the umbrellas utilized arefundamentally susceptible to material fatigue along with fragmentfracture. Furthermore, thromboembolic complications are frequently to beanticipated.

With another type of occlusion device, the so-called Lock-Clamshellumbrella system, two stainless steel, preferably Dacron-covered,umbrellas are provided, each stabilized by four arms. This type ofoccluder is implanted into the patient through a vein. However, seen asproblematic with the Lock-Clamshell occluder is the fact that theinsertion instruments necessary to implant the device need to be ofrelatively large size. A further disadvantage is that many differentoccluder sizes are needed in order to cope with the respectiveproportions of the septal defects to be occluded. It thus turns out thatthe umbrellas do not flatten out completely in the inserted state if thelength or the diameter of the crosspiece inserted into the defect is notof an optimum match. This results in incomplete endothelialization. Ithas furthermore been shown that over a longer period of time, many ofthe systems implanted into patients' bodies will exhibit materialfatigue and fractures in the metallic structures due to the substantialmechanical stresses. This is especially the case given permanent tensionbetween an implant and the septum.

In order to overcome these disadvantages, self-centering occlusiondevices have been developed which are inserted into the body of thepatient and introduced into the septal defect to be occluded by way of aminimally-invasive procedure, for example using a catheter and guidewires. Their design is based on the principle that the occlusion devicecan be tapered to the dimensions of the insertion instrument and/orcatheter used for the intravascular surgical procedure. Such a taperedocclusion device is then introduced by catheter into the septal defectto be occluded, respectively into the shunt of the septum defect to beoccluded. The occluder is then discharged from the catheter, upon whichthe self-expanding umbrellas, retention discs respectively, subsequentlyunfold against the two sides of the septum. The umbrellas in turncomprise fabric inserts made from or covered by, for example, Dacron,with which the defect/shunt is occluded. After a few weeks or months,the body's own tissue more or less completely envelops the implantsremaining in the body.

An example of this type of self-centering occlusion device is known fromUS printed U.S. Pat. No. 5,725,552, which describes an occlusion deviceknown as the “Amplatz occluder.” This known system will be brieflydescribed below with reference to FIGS. 15 a to 15 c. Specifically, FIG.15 a shows a tubular braiding known from the prior art, for example saidUS printed U.S. Pat. No. 5,725,552, as the base structure or startingbody for manufacturing this type of known occlusion device, whereby eachend of the tubular braiding needs to be held in a respective holder.FIG. 15 b depicts a side sectional view of the right side of a knownPFO-type occlusion device from the prior art, for example said USprinted U.S. Pat. No. 5,725,552, with the occlusion device being madefrom a tubular braiding in accordance with FIG. 15 a, while FIG. 15 cshows a right-side sectional view of a further ASD-type occlusion devicelikewise known from US printed U.S. Pat. No. 5,725,552, with thisocclusion device also being made from a tubular braiding in accordancewith FIG. 15 a.

To be understood by the term “PFO-type” as used herein is an occlusiondevice for treating a patent foramen ovale (PFO) while the term“ASD-type occlusion device” refers to an occlusion device for treatingatrial septal defects.

The known occlusion devices consist of a braiding of a plurality offine, intertwined nitinol wire strands in the shape of a yo-yo. Eachbraiding is manufactured in its initial form as a rounded braidinghaving loose wire ends both at its leading end (its proximal side,respectively) as well as at its trailing end (its distal side,respectively). During the subsequent processing of the rounded braiding,these loose ends must then be gathered into a collar and weldedtogether. After the appropriate processing, both the proximal side aswell as the distal side of the finished occluder exhibit a protrudingcollar. Dacron patches are sewn into the distal and proximal retentionumbrellas and the interposed crosspiece. Because of the memory effect ofthe nitinol material used, the two retention umbrellas unfold bythemselves upon exiting the catheter, initially in a balloon-likeintermediate stage, whereby the retention umbrellas ultimatelypositioned on the two sides of the septum eventually assume a more orless flattened form. The crosspiece centers itself automatically intothe shunt to be occluded as the umbrellas expand.

Because the collar protrudes past the proximal retention area of theoccluder, the problem arises that the inserted implant causesembolic-related problems, in particular consecutive embolization.Because portions of the occlusion device protrude past the septum walland are in continuous contact with the blood, defense system reactionsare also a frequent occurrence. Furthermore, a completeendothelialization of the occluder implant is often prevented.

An occlusion device of the type indicated at the outset as well as amethod for manufacturing such an occlusion device is additionally knownfrom WO 2005/020822 A1. The occlusion device described thereinessentially consists of a braiding of thin wires or threads made from amaterial having shape-memory function. In the expanded state, the knownocclusion device exhibits a proximal and a distal retention area as wellas a cylindrical crosspiece interposed between the two.

Because the proximal retention area of the braiding exhibits a formwhich is open to the proximal end in this prior art, it basically allowsthe rim of the proximal retention area to lie flat against the septalwall when the occlusion device is in the inserted state while theretention area does not protrude beyond the septal wall.

The manufacturing process according to WO 2005/020822 A1 utilizes abraiding technique which forms a tubular braiding open to the top, whichneed only be provided with a holder for bundling the braiding's threadsor wires on one end, while at the opposite end, the braiding's threadsor wires are intertwined from their center. It thus becomes possible toproduce a braiding to serve as the base structure for the knownocclusion device, whereby the proximal retention area of the basestructure exhibits a form open to the proximal end.

To further define the occlusion device known from WO 2005/020822 A1 morespecifically, particular reference is made to FIGS. 16 a to 16 c. Indetail, FIG. 16 a shows a tulip or bell-shaped braiding having a distalholder known, for example, from WO 2005/020822 A1. FIG. 16 b depicts asectional view of the right side of a PFO-type occlusion device knownfrom WO 2005/020822 A1, whereby the occlusion device is made from atubular braiding in accordance with FIG. 16 a. FIG. 16 c finally showsanother sectional view of the right side of an ASD-type occlusion deviceknown from WO 2005/020822 A1, with the occlusion device likewise beingmade from a tubular braiding in accordance with FIG. 16 a.

In the case of these occlusion devices known from WO 2005/020822 A1, ithas proven disadvantageous for the braiding on the proximal end toexhibit an opening which needs to be spanned by, for example, a Dacroninsert or a cloth so that the finished occlusion device will no longerbe open at its proximal end. Producing such an occlusion devicenecessitates quite a complex manufacturing process, and one which isthereby cost-intensive. Furthermore, different materials, namely thematerials of the braiding and of the Dacron insert or cloth need to beforce-fit to one another. Such joints are inherent weak points in termsof material fatigue. Thus, this known type of occluder has an increasedrisk of material fatigue along with fragment fracture. It hasfurthermore been shown that such an implanted system can exhibitmaterial fatigue and fractures in the joints between the metallicstructures and the Dacron insert after a longer period of time within apatient's body, stemming from the considerable mechanical stresses. Thisis especially the case when there is permanent tension between thebraiding and the insert.

Moreover, thromboembolic complications need to be considered with theocclusion devices known from WO 2005/020822 A1. While the known systemenables the rim of the proximal retention area to lie flat against theseptal wall and not have the retention area project beyond the septalwall when the occlusion device is in the inserted state, the proximalend of the known occlusion device nevertheless exhibits amanufacturing-contingent opening at the proximal wall axial to thecrosspiece. Even if this opening is—as described above—closed with aDacron insert, for example, the known system cannot prevent the finishedocclusion device from having at least one remaining trough-shaped recessor sometimes even components protruding in the proximal retention areaof the occluder, these being at the very location where the openingclosed with the Dacron insert is disposed.

Along with trough-shaped recesses and protruding components comes yetanother problem, that of the inserted implant causing embolic-relatedproblems, in particular consecutive embolization. These embolic-relatedproblems arise especially when the patient is suffering from so-calledatrial fibrillation of the heart. This is a condition in which frequentexcitation of the heart's upper chambers results in their notcontracting. As a consequence of the left and right halves of the heartbeing deprived of contraction, the blood is ineffectively swirled andmixed and thrombi can form in the atrium. A considerable risk whenatrial fibrillation causes thrombi to form in the atrium is that thesethrombi can be carried along in the bloodstream and enter the arterialcirculation. Apoplectic strokes, occurring in approximately 5% of atrialfibrillation patients each year, are a particular consequence of thisembolization when not chronically treated with so-called dicumerol, ablood anticoagulant. However, anticoagulating the blood with so-calleddicumerol is also not without risks. One side effect of dicumeroltreatment is increased bleeding such that there are contraindicationsfor this treatment for approximately 20% of all atrial fibrillationpatients and the patients thus have to hazard the risk of a stroke whenweighing the bleeding/stroke risk.

The present invention therefore addresses the problem of refining suchan occlusion device as known to medical technology and described in WO2005/020822 A1 so as to overcome the disadvantages cited above. Aparticular objective is the providing of an occlusion device applicableto occluding defects of different sizes, whereby implantation of theoccluder is to be a simple procedure. Furthermore, the occurrence ofsuch usual occluder complications such as dislocation, partialembolization or occluder material fatigue is to be reduced to thegreatest extent possible. Above and beyond that, an occlusion device isto be provided which ensures occlusion of a septal defect with as fewportions of the occlusion device as possible protruding past the septumwall so as to avoid the associated and above-cited complications.

Based on the problem as posed and starting out from the system as knownfrom WO 2005/020822 A1, it is the task of the present invention toprovide an occlusion device which lies as flat as possible against theseptum in the inserted state at the proximal side of the septal defect,and with which the risk of material fatigue with fragment fracture isconsiderably reduced, and to do so at a lower manufacturing cost. Thepresent invention moreover has the technical task of providing a methodfor manufacturing such an occlusion device.

These tasks are solved in accordance with the invention by an occlusiondevice of the type specified at the outset having the proximal retentionarea of the braiding exhibit a completely closed proximal wall at theproximal end of the occlusion device with a continuous surface formingthe proximal end of the occlusion device.

The problem of process-engineering the present invention is furthermoresolved by a method for manufacturing the above-cited occlusion devicewhich is characterized by the process step of forming a ball-shaped,bulb-shaped or teardrop-shaped hollow braiding by means of a braidingprocess known per se and by the process step of forming a proximalretention area and a distal retention area at the bundled first end, andinterposing a cylindrical crosspiece between said proximal and distalretention areas. It is thereby provided for the hollow braiding to bebundled at a first distal end and to exhibit a completely closedproximal wall having a continuous surface on an opposite second proximalend.

To be understood by the term “proximal wall” as used herein is thatsegment or region of the proximal retention area of the braiding at theproximal end of the occlusion device which forms the closure for thedefect to be occluded on the proximal end.

The particular advantages of the invention lie in providing anintravascular occlusion device, especially for the treatment of septaldefects, whereby the occluding device is suited to be administered bycatheter to the defect to be occluded. Because the proximal retentionarea of the braiding has a fully closed proximal wall at the proximalend which exhibits a continuous surface forming the proximal end of theocclusion device, a particular advantage afforded by the occlusiondevice—independent of the diameter size to the defect to be occluded andindependent of the septal wall's thickness—is in its self-adjusting tothe defect in the septal wall and doing so specifically that no portionof the occlusion device protrudes into the plane of the septal wallhaving the defect on the proximal side of the defect. In the inventivesolution, this plane; i.e., the plane of the septal wall with thedefect, is formed by the fully closed proximal wall of the occlusiondevice. On the other hand, the inventive solution ensures that thisproximal wall will contain no recesses or other “discontinuities” in themathematical sense such as sharp edges, kinks, etc. whatsoever, so thatthe usual associated complications, in particular as regardsembolic-related problems, can no longer occur.

Above all to be achieved is that the inserted occlusion device will befully enveloped by the body's own tissue substantially faster than isthe case with the occluding systems known in the prior art. The furtheradvantage of better mechanical stability over the long term compared tothe systems known in the prior art is a function derived from using abraiding made of thin wires or threads as the starting material for theinventive occlusion device. This largely prevents fractures fromoccurring in the structure of the inserted implant. The braidingfurthermore has a better rigidity since the entire structure is madefrom one material and without any connecting joints.

Especially due to the inventive solution being able to completelydispense with fabric or Dacron inserts, as is the case for example withthe occluder system pursuant WO 2005/020822 A, the premature developmentof material fatigue can be effectively further reduced, whereby even theoverall manufacturing costs can be additionally lowered.

The fully closed proximal wall provided at the proximal retention areaof the braiding additionally allows the proximal retention area of thedevice to flatten completely against the lateral edge of the defect inthe inserted state and to specifically do so virtually independently ofthe diameter to the defect or the thickness of the septal wall. As aresult, the occlusion device can be used for a wide range ofdifferently-sized septal defects. Because there is then no need for aholder for the bundled or gathered braiding at the proximal retentionarea, there are also no components of the occlusion device to protrudebeyond the septal wall which prevents the components of the implant frombeing in continuous contact with the blood. This yields the advantage ofthere being no threat of the body mounting any defense mechanismreactions or of there being any thromboembolic complications.

The inventive method affords the prospect of realizing a particularlysimple manufacturing of the occlusion device described above. First, aball-shaped, bulb-shaped or teardrop-shaped hollow braiding is formed,for example using a round braiding machine. The technology used here isone in which the configured braiding is bundled at the trailing end ofthe length of the braiding; i.e., at what will later be the distal endof the occlusion device, while the leading end of the length of thebraiding; i.e., what will later be the proximal end of the occlusiondevice, is closed. It is thereby possible to manufacture a “bag-shaped”hollow braiding, the bundled end of which corresponds to the distal endof the finished occlusion device and its opposite closed end theproximal end or the proximal wall of the finished occlusion device.Because a known braiding method is used to produce the occlusion device,the finished occlusion device exhibits mechanical properties in termsof, for example, expansion, stability, strength, etc., which can becustom-adapted to the later use of the occlusion device. In advantageousmanner, metallic wires or even organic threads can be incorporated intothe braiding. It goes without saying that the terms as used herein of“ball-shaped,” “bulb-shaped,” “teardrop-shaped” and “bag-shaped” are torespectively refer to forms which have shapes comparable to a ball, abulb, a teardrop or a bag. The invention is in particular not limitedsolely to an exact spherical shape, etc.

With respect to the occlusion device itself, preferred embodiments ofthe invention are specified in subclaims 2 to 10 and, with respect tothe manufacturing process, in subclaims 12 and 13.

It is particularly preferred for the proximal wall of the occlusiondevice to exhibit a curved surface as the continuous surface. It ishereby essential that the curvature to this surface have nodiscontinuities such as, for example, edges, corners, etc. With respectto the term “continuity” as used herein, this refers to the mathematicaldefinition of a continuous surface as known in the field of topology.For example, it would be conceivable for the proximal wall to exhibit acurved surface which in respect to the plane of the septal wall with thedefect, has a preferably slightly concave curve so as to ensure aparticularly good, i.e. flat and even fitting of the proximal wallagainst the septal wall. It is of course also conceivable that thesurface of the proximal wall be preferably configured to be slightlyconvex relative the septal wall, this thereby achieving that theforce-fit connection between the proximal wall, the peripheral area ofthe proximal wall respectively, and the septal wall at the defect to beoccluded is particularly large so as to thus enable a better anchoragefor the occlusion device in the defect to be occluded. It would also beconceivable for the outer region of the proximal wall to be formed witha slight concave which transitions into a convex form toward the middle;i.e. toward the position axial to the crosspiece of the occlusiondevice. This can also yield advantages, especially as regards anchoringthe occlusion device in the defect to be occluded.

A particularly preferred realization of the latter embodiment in whichthe proximal wall of the occlusion device exhibits a curved surface asthe continuous surface provides for the curved surface to conform to thesurface of a section of a ball-shaped, bulb-shaped or teardrop-likebody. In other words, this means that the proximal wall of the occlusiondevice can be configured in the shape of a spherical cap or a segment ofa teardrop, for example. Of course, other profiles are just asconceivable here. Of particular advantage is that the inventive solutionbasically allows for the optimum use of an occlusion device independentof the type and in particular of the size of the defect to be occluded.

It is of particular preference for the occlusion device to have thebraiding consist of nitinol or of another shape-memory material ormaterial having memory effect. Such other material could conceivably be,for example, copper-zinc-aluminum alloys, gold-cadmium alloys or evenferrous alloys such as e.g. iron-manganese-silicon alloys, or alsoplastics, all of which are characterized by their extremely high memorycapacity.

It is particularly preferably provided for the braiding of the inventiveocclusion device to be formed from a shape-memory polymer based on, forexample, a polyanhydride matrix or on a polyhydroxycarboxylic acid.These are synthetic degradable materials which have a thermally-inducedshape-memory effect. Yet also conceivable would be other shape-memorypolymers such as, for example, block copolymers as described for examplein the special edition of Angewandte Chemie ¹ 2002, 114, pages 2138 to2162, by A. Lendlein and S. Kelch.¹ “Applied Chemistry”

By making use of such a material, it is possible to utilize a bag-shapedhollow braiding which is closed at its one end and open and bundled atits other end for the starting body of the occlusion device, producedfor example in a round braiding method. Said starting body is thensubsequently brought into the desired form for the occlusion device bymeans of a molding and heat treatment procedure. Other treatmentprocedures are of course also conceivable here.

An advantageous further development of the latter described embodimentof the inventive occlusion device in which the braiding is made from ashape-memory material provides for the material to be a biodegradableshape-memory polymer material. Synthetic biodegradable implant materialis particularly suitable. Such degradable materials or polymers containcleavable bonds under physiological conditions. “Biodegradableness”refers to material degraded by or in a biological system based on lossof mechanical property. Under certain conditions, the outer shape aswell as the dimensions of the implant are preserved during thisdegradation. If one speaks of a degradation time without adding anyadditional quantifying information, this refers to the time it takes forthe complete loss of the mechanical property. Biostable materials referto those which remain stable in biological systems and at least partlydegrade in same over the long term.

In the case of degradable polymers, there is a differentiation to bemade between hydrolytically and enzymatically degradable polymers.Hydrolytic degradation has the advantage that the rate of degradation isindependent of the implantation site since water is present everywhere.In contrast, local enzyme concentrations differ greatly. Withbiodegradable polymers or materials, degradation thus ensues from purehydrolysis, enzymatically-induced reactions or through a combination ofthe two. Typical hydrolyzable chemical bonds are amide, esterase oracetal bonds. When degrading, two mechanisms can be observed. Withsurface degradation, the hydrolysis of chemical bonds occurs solely onthe surface. Due to its hydrophobic nature, polymer degradation occursfaster than the water diffusion inside the material. This mechanism isabove all observed with poly(anhydride)s or poly(orthoester)s. For thepoly(hydroxy carboxylic acid)s such as poly(lactic acid)s orpoly(glucose acid)s, the corresponding copolymers respectively, whichare of predominant importance for the shape-memory effect, the entirevolume of the polymer will degrade. The element determining the rate ishereby the hydrolytic bond cleavage since water diffusion occursrelatively quickly in the rather hydrophilic polymer matrix. Crucial tothe use of biodegradable polymers is that, on the one hand, thedegradation rate be controlled or variable and, on the other, that theproducts of degradation are non-toxic.

The invention claims all the afore-mentioned biodegradable shape-memorypolymers.

It is particularly preferred in one development of the inventiveocclusion device to have the braiding of the occlusion device taper tothe diameter of a catheter to be used in the minimally-invasive surgicalprocedure. The advantage to this embodiment is in particular to be seenin that the catheter system used for implantation and explantation canhave a considerably reduced inner diameter, which above allsignificantly increases maneuverability of the occlusion device to beimplanted. This thus improves the accuracy when positioning the devicein the defect to be occluded. In the case of an occluder made fromnitinol, the inner diameter of the catheter to be used duringimplantation or explantation ranges between 8 to 10 Frenches, whereas inthe case of occlusion devices made from polymer synthetics, the innerdiameter only need be between 6 and 8 Frenches.

With respect to the latter cited preferred embodiment of the inventivesolution according to which the braiding of the occlusion device tapersto the diameter of the catheter used in an intravascular surgicalprocedure, a further development provides for the proximal retentionarea of the occlusion device with its proximal wall to be configuredsuch that the proximal wall curves outward upon the occlusion deviceexpanding so as to come into position in such manner with the septalwall. This reflects a particularly simple to realize and therebyeffective way to form the proximal wall in the occlusion device. It isthus possible to form the entire occlusion device as one single piece ofbraiding so that no mechanical connecting elements are needed betweenthe proximal wall and the crosspiece on the one hand and, on the other,the dimensions of the occlusion device in the folded state can befurther minimized. Of course, other embodiments for forming the proximalwall at the proximal retention area are just as conceivable here.

So that the inventive occlusion device will exhibit the functionality ofretrievability, a preferred further development of the occlusion deviceprovides for the distal retention area to exhibit a holder, preferablyarranged axially to the crosspiece, whereby the holder has at least oneconnecting element engageable with a catheter. With this connectingelement, which is preferably arranged on the distal end of the occlusiondevice such that it does not project over the distal end of the septalwall, preventing the components of the implant from being in continuouscontact with the blood, explanting the occlusion device according tothis further development becomes a simple process. A connecting elementwhich can engage with a catheter meanwhile facilitates the implantingand positioning of the occlusion device (folded during the implantationprocedure) in the septal defect to be occluded. Various differentmechanisms are conceivable as connecting elements such as engagingmembers, for example, or even hooks and/or eyelets which can beforce-fit to the corresponding complementary-configured connectingelements of a catheter.

Another advantageous further development provides for the occlusiondevice to be configured to be reversibly foldable and expandable so thatthe device in its expanded state can be folded back up again, forexample with the aid of an explantation catheter, whereby the force-fitconnection between the proximal wall formed at the proximal retentionarea, the peripheral area of the proximal wall respectively, and theseptal wall can be disengaged. It is thereby conceivable duringexplantation for a catheter to engage with a connecting element at thedistal end of the occlusion device for example, with the folding of theocclusion device being effected by external manipulation aided by thecatheter. The occlusion device is thus completely reversibly retractablein the catheter, which enables the complete removal of the device.

The method according to the invention affords the prospect of realizinga particularly simple manufacturing of the occlusion device describedabove. First, a ball-shaped or bag-shaped hollow braiding is formed,using for example a round braiding machine as has already been describedin the WO 2005/020822 A1 patent application. However, a special braidinghead is necessary to do so, which will be described in greater detailbelow with reference to the figures. The technology used in particularhere is one in which the configured braiding is bundled at the trailingend of the length of the braiding; i.e., at what will later be thedistal end of the occlusion device, while the leading end of the lengthof the braiding; i.e., what will later be the proximal end of theocclusion device, is closed. It is thereby possible to produce aspherical or bag-like hollow braiding, the bundled end of whichcorresponds to the distal end of the finished occlusion device and theopposite closed end to the proximal end of the finished occlusiondevice. The finished occlusion device exhibits mechanical properties interms of, for example, expansion, stability, strength, etc., which canbe custom-adapted to the later use of the occlusion device. Inadvantageous manner, metallic wires or even organic threads can beincorporated into the braiding.

With respect to the method, it is preferably provided for the processstep of forming the retention area and the crosspiece to include aprocedural molding and heat treatment step. This is of particularadvantage when the ball-shaped hollow braiding formed is made fromnitinol or another material which has shape-memory properties or effect.Preferably provided for the inventive occlusion device is forming thebraiding from a shape-memory polymer which is based on a polyanhydridematrix or a polyhydroxy-carboxylic acid, for example. These aresynthetic degradable materials which have a thermally-inducedshape-memory effect. Yet other shape-memory polymers such as for exampleblock copolymers would also be conceivable. The essential point is thatsuch materials can be readily and simply brought into their applicablefinal form using a combination of molding and heat treatment steps. Afinished occluder can then be tapered to the dimensions of a catheter,for example. After exiting the catheter, the occlusion device thenunfolds by itself and again assumes that profile to the ball-shapedhollow braiding to which the occlusion device was molded during themanufacturing process in the molding and heat treatment step.

It is preferred for the ball-shaped hollow braiding to be manufacturedin such a manner that the thin threads or wires constituting thefinished braiding intertwine at the proximal end of said braiding whenthe ball-shaped hollow braiding is formed. This represents a conceivableand especially simple manner of producing an occlusion device inaccordance with the present invention, the proximal retention area ofwhich exhibits a closed, flat form to the proximal end (proximalsurface). Of course, other manufacturing methods are naturally alsoconceivable.

The following will make reference to the drawings in providing a moreprecise detailing of preferred embodiments of the inventive occlusiondevice as well as of a round braiding machine to provide clarificationof the inventive manufacturing method for the occlusion device byexample.

Shown are:

FIG. 1 a perspective view of a preferred first embodiment of anocclusion device according to the present invention in expanded state inwhich only the outlined contour of the occlusion device is depicted;

FIG. 2 a perspective detail view of the distal retention area of thefirst embodiment of the FIG. 1 occlusion device in the expanded state;

FIG. 3 a side view of the inventive occlusion device shown in FIG. 2 inthe expanded state;

FIG. 4 a three-dimensional view of a round braiding machine toillustrate the inventive manufacturing method for the occlusion device;

FIG. 5 a top plan view onto the round braiding machine depicted in FIG.4 to illustrate the inventive manufacturing method for a ball-shaped,bulb-shaped or teardrop-shaped base braiding structure in accordancewith FIGS. 9 a-9 c, which can serve as a base structure for theocclusion device according to the present invention;

FIG. 6 a detail view of the braiding head of the round braiding machinedepicted in FIG. 4;

FIG. 7 an example of a braiding produced with the braiding head shown inFIG. 6, which can serve as the base structure for the occlusion deviceaccording to the present invention;

FIG. 8 a a side view of a special braiding head for manufacturing aball-shaped, bulb-shaped or teardrop-shaped base braiding structure inaccordance with FIGS. 9 a-9 c, which can serve as the base structure forthe occlusion device according to the present invention;

FIG. 8 b a sectional view of the braiding head according to FIG. 8 a;

FIG. 8 c a stereoscopic representation of the special braiding head usedto produce a spherical braiding;

FIG. 9 a a perspective representation of a base body for a sphericalbraiding constituting the initial body for the inventive occlusiondevice, whereby the base body is configured in a form as close to a ballas possible;

FIG. 9 b a perspective representation of a base body for a sphericalbraiding suited for producing the occlusion device according to thepresent invention and whereby the base body is configured to thegreatest extent possible in the form of a bulb-shaped body;

FIG. 9 c a perspective representation of a base body for a sphericalbraiding, whereby the base body is suited for producing the occlusiondevice according to the present invention and whereby the base body isconfigured in a teardrop-shaped form;

FIG. 10 a a spherical braiding as a base body for different occlusiondevices in accordance with the present invention which is produced witha special braiding method and which exhibits a distal holder;

FIG. 10 b a sectional side view of the right side of an inventivePFO-type occlusion device, whereby the occlusion device is made from aspherical braiding in accordance with FIG. 9 a;

FIG. 10 c a sectional side view of the right side of an inventiveASD-type occlusion device, whereby the occlusion device is made from aspherical braiding in accordance with FIG. 9 a;

FIG. 11 a sectional side view of the right side of an inventive PFO-typeocclusion device, whereby the occlusion device is made from aball-shaped, bulb-shaped or teardrop-shaped base braiding structure inaccordance with FIGS. 9 a-9 c and comprises a distal holder;

FIG. 12 a sectional side view of the right side of an inventive VSD-typeocclusion device, whereby the occlusion device is made from aball-shaped, bulb-shaped or teardrop-shaped base braiding structure inaccordance with FIGS. 9 a-9 c and comprises a distal holder;

FIG. 13 a sectional side view of the right side of an inventive ASD-typeocclusion device according to the invention, whereby the occlusiondevice is made from a ball-shaped, bulb-shaped or teardrop-shaped basebraiding structure in accordance with FIGS. 9 a-9 c and comprises adistal holder;

FIG. 14 a sectional side view of the right side of an inventive PDA-typeocclusion device, whereby the occlusion device is made from aball-shaped, bulb-shaped or teardrop-shaped base braiding structure inaccordance with FIGS. 9 a-9 c and comprises a distal holder;

FIG. 15 a a tubular braiding known from the prior art, for example inaccordance with US printed U.S. Pat. No. 5,725,552, constituting thestarting structure or base for manufacturing a known occlusion device,whereby the respective ends of the tubular braiding need to be held in aholder;

FIG. 15 b a sectional side view of the right side of a PFO-typeocclusion device known from the prior art, for example in accordancewith US printed U.S. Pat. No. 5,725,552, whereby the occlusion device ismade from a tubular braiding in accordance with FIG. 15 a;

FIG. 15 c a sectional side view of the right side of an ASD-typeocclusion device known from the prior art, for example in accordancewith US printed U.S. Pat. No. 5,725,552, whereby the occlusion device ismade from a tubular braiding in accordance with FIG. 15 a;

FIG. 16 a a tulip-shaped or bell-shaped braiding having a distal holderas known from the prior art, for example from WO 2005/020822 A1;

FIG. 16 b a sectional side view of the right side of a PFO-typeocclusion device known from the prior art, for example in accordancewith WO 2005/020822 A1, whereby the occlusion device is made from atubular braiding in accordance with FIG. 16 a; and

FIG. 16 c a sectional side view of the right side of an ASD-typeocclusion device known from the prior art, for example in accordancewith WO 2005/020822 A1, whereby the occlusion device is made from atubular braiding in accordance with FIG. 16 a.

FIG. 1 shows a perspective view of a preferred first embodiment of theocclusion device 1 according to the invention in the expanded state,whereby only the outlined contour of occlusion device 1 is depicted inFIG. 1. FIG. 2 shows a perspective detail view of the distal retentionarea 8 of the first embodiment of the occlusion device 1 shown in theexpanded state in FIG. 1. FIG. 3 shows a side view of the inventiveocclusion device 1 shown in expanded state in FIG. 2.

The occlusion device 1 essentially consists of a braiding 2 of thinwires or threads 4, preferable made from nitinol or another shape-memorymaterial or material having memory effect. The braiding 2 exhibitssufficient flexibility such that the occlusion device 1 can be taperedto the diameter of a (not explicitly shown) catheter used in anintravascular surgical procedure. Because of the material's memoryeffect, the occlusion device 1 tapered as such has a shape-memoryfunction such that the device 1 self-expands after exiting the catheterand reassumes the predefined form which corresponds to its use. Thisnormally ensues after the occlusive device 1 initially disposed in thecatheter has been positioned at the location to be treated.

As especially shown in FIGS. 2 and 3, the occlusion device 1 exhibits aproximal retention area 6, a distal retention area 8 and a cylindricalcrosspiece 10 arranged between said proximal and distal retention areas6, 8 in the expanded state. The two retention areas 6, 8 serve toocclude a defect or shunt in a septum. This ensues by areas 6, 8positioning against the two sides of the shunt to be occluded while thecrosspiece 10 passes through the shunt. The occlusion device 1 accordingto the invention therefore represents an occluding system which can beintroduced into a patient's body and positioned at its intended locationin a minimally-invasive procedure; i.e., using a catheter and guidewires, for example.

The design to the inventive occlusion device 1 is thereby based on theprinciple of having the occlusion device 1 taper to the dimensions ofthe catheter. After being discharged from the catheter, the retentionareas 6, 8 then unfold by themselves, thereby positioning themselves onboth sides of the septum. The inventive design moreover reflects theocclusion device 1 being a self-positioning and self-centering system.The crosspiece 10 thereby has the length of the atrial diaphragm, theseptum respectively, in order to ensure secure placement of retentionareas 6, 8 at the septum wall.

Unlike conventional occlusion systems known from the prior art in whicha self-expanding umbrella serves as proximal retention area 6, theproximal retention area 6 of the present invention has a flat coveringin the form of a proximal wall 112 closed to the proximal end 12 suchthat no material of the implanted occlusion device 1 whatsoever canextend past the septum wall in the proximal area of the patient's organ.The closed contouring to the proximal end 12 of proximal retention area6 further ensures that the rim of proximal retention area 6 will alwayslie flush with the septum wall. This occurs over a relatively wide areaindependent of the diameter to the defect or the thickness of the atrialdiaphragm, the septum respectively, and thereby allows completeendothelialization to occur relatively quickly after the occlusiondevice 1 has been implanted and precludes any possible defense mechanismreactions from the patient's body since the blood is effectivelyprevented from coming into contact with the material of implant 1.

Because of the self-expanding property to implant 1 based on the memoryeffect of the material used, the occlusion device 1 according to theinvention exhibits a self-centering function in the shunt or the septaldefect. The occlusion device 1 can furthermore be retracted at any timeup to the uncoupling of the guide wires of the insertion instrument.

The occlusion device 1 according to the invention can of coursefurthermore comprise fabric inserts, which are not explicitly shown inthe present drawings, the principle behind which is known from the priorart. Such fabric inserts consist mostly of Dacron material. Chemicallyspeaking, Dacron is a polyethylene terephthalate polyester, obtained bypolycondensating ethylene glycol and terephthalic acid—dimethyl ester.It is hereby conceivable to incorporate the fabric inserts within theinterior of crosspiece 10 or at the proximal end 12 of retention area 6in order to be able to fully occlude the defect or the shunt in theseptum wall. The fabric inserts can be incorporated by bracing samewithin occlusion device 1, for example. The implant 1 inserted into thebody will then be completely enveloped by the body's own tissue within afew weeks or months.

The braiding 2 which serves as the base structure for the occlusiondevice 1 according to the invention exhibits sufficient rigidity toclamp the fabric insert and have it remain in position.

The braiding 2 converges into a holder 5 at the distal end 3 of distalretention area 8. This is thereby realized by producing an internalthread in holder 5 which then serves to engage with a guide wire of anot shown insertion instrument when the occlusion device 1 is beingguided to the appropriate position relative the location of the defectin the septum, for example in an intravascular surgical procedure. Afterthe occlusion device 1 has been positioned in the shunt or defect, theengagement between the guide wire of the insertion instrument and distalend 3 is then disengaged. It is, of course, also conceivable to make useof a differently-configured mechanism in place of an internal thread inholder 5 at distal end 3.

As already indicated, FIG. 1 shows a perspective view of the preferredfirst embodiment of the occlusion device 1 according to the invention inexpanded state while FIG. 2 shows a perspective partial view of thedistal retention area 8 of the occlusion device 1 shown in FIG. 1. Forsimplification purposes, FIG. 1 only shows the outline of occlusiondevice 1. For even further simplification, a detailed depiction of thebraiding 2 serving as the base structure is dispensed with and the formof occlusion device 1 is shown as that of a closed surface. Thisocclusion device 1 exhibits a much flatter proximal retention area 6compared to the first embodiment. Depending upon actual intendedapplication, the proximal retention area 6 is configured in a more orless distinctly flattened shape so as to ultimately form the proximalwall 112 in the expanded state. Yet also conceivable would be for theproximal wall 112 to exhibit a completely flattened spherical shape oran almost plate-shaped profile.

FIG. 4 shows a three-dimensional view of a round braiding machine 7 inorder to illustrate the method of manufacturing the occlusion device 1according to the present invention. FIG. 5 is a top plan view of theround braiding machine 7 depicted in FIG. 4 in order to illustrate theinventive manufacturing method for a ball-shaped, bulb-shaped orteardrop-shaped initial braiding structure 2 according to FIGS. 9 a-9 c,which can serve as the starting structure for the occlusion device 1according to the invention. FIG. 6 further shows a braiding head 11 forthe round braiding machine 7 of FIG. 4 in greater detail, while FIG. 7shows a braiding 2 made for example with the braiding head 11 shown inFIG. 6, which can serve as the base structure for the occlusion device 1according to the invention. FIG. 8 a is furthermore a side view of aspecial braiding head 11 for manufacturing a ball-shaped, bulb-shaped orteardrop-shaped initial braiding 2 according to FIGS. 9 a-9 c, whichlikewise can serve as the base structure for the inventive occlusiondevice 1. The braiding head 11 according to FIG. 8 a is further shown insectional view in FIG. 8 b, while FIG. 8 c depicts a stereoscopicrepresentation of the special braiding head 11 for manufacturing aspherical braiding of this type.

In contrast to the known braiding methods where all the threads or wires4 are gathered into one bundle at the leading end of the braiding 2 andstretched to an extractor device, in the method according to theinvention, the material supply is stretched from every second spool 9 toa braiding head 11 and from there to each next respective spool 13 or amultiple of the dividing gap. The spools 13 not having a material supplyonly have an auxiliary thread extending at least to braiding head 11.The end of the material supply is connected to the end of the auxiliarythread as close as possible to the auxiliary thread spool by means ofbolt 14.

The braiding head 11, depicted in detail in the latter cited figures, isof crown-shaped configuration and is provided with form elements 15which allow the threads or wires 4 to be hooked. Form elements 15 can belowered in order to hook/unhook braiding 2. Braiding head 11 is axiallypositioned at the center of the orbit of impellers 16 such that thethreads or wires 4 are aligned at a flat downward angle to bobbins 17 ofthe braiding machine 7.

After all the wires 4 required for the braiding 2 have been joined andtightened, braiding commences in conventionally known manner in thatimpellers 16 rotate around the center while bobbins 17 shift fromimpeller to impeller, their orbits thereby crossing. The infeed forbraiding 2 is realized by means of a cam plate 18 based on therevolutions of impellers 16. The length to the braiding which can beproduced with this method is proportional to the circumference and pitchof braiding 2 as well as to the length of the end of the wire or threadconnected to the auxiliary thread. Subsequent braiding, the free endsare bundled or gathered, lopped off from the material supply anduncoupled from the auxiliary thread. The ball-shaped or bag-like hollowbraiding 2 thus produced is closed at its leading end and bundled at itstrailing end. The wire bundle is gathered such that an internal threadcan be produced therein for engaging with the guide wire of a insertioninstrument.

In the subsequent material-dependent molding and heat treatment process,the braiding 2 is brought into the form desired for occlusion device 1.The initial structure is suitable for manufacturing an occlusion device1 for the treatment of a patent foramen ovale (PFO), ventricular septaldefect (VSD), atrial septal defect (ASD) or persistent ductus arteriosus(PDA).

It is noted at this point that FIG. 10 b, for example, shows a sidesectional view of the right side of an inventive PFO-type occlusiondevice 1, whereby this PFO-occlusion device 1 is made from a sphericalbraiding 2 as described above. FIG. 10 c moreover shows a side sectionalview of the right side of an inventive ASD-type occlusion device 1,whereby this ASD-occlusion device 1 as well is made from a sphericalbraiding 2, the manufacture of which is described above. FIG. 11furthermore shows another side view of an inventive PFO-type ofocclusion device 1.

It is furthermore pointed out that FIG. 12 discloses a side sectionalview of the right side of an inventive VSD-type occlusion device 1,whereby this VSD-occlusion device 1 is made from a ball-shaped,bulb-shaped or teardrop-shaped initial braiding 2 as described above.Finally, reference is made to FIGS. 13 and 14 which respectively depictsectional views of the right sides of occlusion devices 1 of the ASD andPDA types. The inventive occlusion devices shown in FIGS. 13 and 14 arein turn made from a ball-shaped, bulb-shaped or teardrop-shaped initialbraiding structure in accordance with FIGS. 9 a-9 c, whereby saidinitial braiding is produced as described above.

From the perspective of holder 5 and depending upon configuration, anexpanded diameter (i.e. distal retention area 8) is formed, followed bycrosspiece 10, to which another expanded closed diameter (i.e. proximalretention area 6, proximal wall 112 respectively) is joined.

Since circumstances dictate that braiding 2 serving as the base for theocclusion device 1 cannot as such always fully occlude a defect, fabricinserts can be introduced into crosspiece 10 and in the expandingdiameters—distal and/or proximal retention areas 6, 8. These fabricinserts, preferably of Dacron, then close the gaps remaining in braiding2 when occlusion device 1 is in its inserted state. Said fabric insertscan be secured for example by being stretched over the proximal openinglike a cloth.

Reference is herewith again made to FIG. 6 which depicts the braidinghead 11 of the round braiding machine 7 from FIG. 4 in greater detail,while FIG. 7 shows an example of a braiding 2 produced with the braidinghead 11 shown in FIG. 6, which can serve as the starting structure forthe occlusion device 1 according to the invention. Clearly to be seenhere is that the braiding 2 serving as the base structure for occlusiondevice 1 is configured in the form of a tubular or bag-shaped braiding 2closed to it top which only needs to be provided with one holder 5 atits end 3, while the threads or wires 4 on the opposite side 12 are, forexample, intertwined from the center outward.

The closed braiding 2 can be shaped as a ball (cf. FIG. 9 a), a bulb(cf. FIG. 9 b) or also a teardrop (cf. FIG. 9 c), whereby only oneholder 5 having an internal thread for snugly connecting with aninsertion catheter is provided at distal end 3.

The core but also highly specific occlusion device 1 can be manufacturedfrom the ball-shaped (FIG. 9 a), bulb-shaped (FIG. 9 b) orteardrop-shaped (FIG. 9 c) initial braiding structure 2, as will bedescribed below, whereby this inventive occlusion device 1 can be givensubstantially improved functional properties such as in particular theextreme flattened form to the proximal wall 112 and without anyadditional seams in proximal retention area 6, proximal wall 112respectively.

Specifically, this is an occluder 1 for treating an atrial septal defect(ASD), which is a hole in the heart's atrial septum. FIG. 13 shows anexample of such an ASD-occluder 1.

Occluder 1 can moreover be produced to treat a patent foramen ovale(PFO); i.e. for treating oval openings/apertures in the heart's atrialseptum. FIG. 11 shows this type of inventive PFO-occluder.

It is moreover conceivable in accordance with the invention, tomanufacture an occluder to treat persistent ductus arteriosus (PDA),meaning to treat an open channel between the aorta and the pulmonaryartery. FIG. 14 depicts this type of PDA-occluder 1.

It is also pointed out in conclusion that, according to the invention,an occluder 1 for treating a ventricular septal defect (VSD) is alsoconceivable; i.e. for treating a hole in the heart's ventricular wall.FIG. 12 shows an example of such a VSD-occluder.

Attention is drawn to the fact that realizing the invention is notlimited to the embodiments specified by the figures, but is insteadfeasible in a plurality of variants.

List of Reference Numerals

-   1 occlusion device-   2 braiding-   3 distal end-   4 thread, wire-   5 holder-   6 proximal retention area-   7 braiding machine-   8 distal retention area-   9 spool-   10 crosspiece-   11 braiding head-   12 proximal end-   13 spool-   14 bolt-   15 form element-   16 impeller-   17 bobbin-   18 cam plate

1. An occlusion device consisting of a holder and a braiding of thinwires or threads, which is given a suitable form in a molding and heattreatment procedure, having a proximal retention area and a distalretention area, wherein the ends of the wires or threads converge into aholder in the distal retention area, and a cylindrical crosspieceinterposed between said proximal and distal retention areas, wherein thetwo retention areas are positioned on the two sides of a shunt to beoccluded in a septum usually by way of an intravascular surgicalprocedure while said crosspiece transverses the shunt, characterized inthat the proximal retention area of braiding exhibits a completelyclosed proximal wall having a continuous surface at the proximal end ofthe occlusion device which forms the proximal end of said occlusiondevice.
 2. The occlusion device according to claim 1, wherein theproximal wall exhibits a curved surface as the continuous surface. 3.The occlusion device according to claim 2, wherein the curved surfaceconforms to the surface of a section of a ball-shaped, bulb-shaped orteardrop-like body.
 4. The occlusion device according to claim 1,wherein the braiding consists of nitinol or another material havingshape-memory or memory effect.
 5. The occlusion device according toclaim 4, wherein the shape-memory material is a biodegradable material.6. The occlusion device according claim 1, wherein the braiding tapersto the diameter of a catheter to be used in an intravascular surgicalprocedure.
 7. The occlusion device according to claim 6, wherein theproximal retention area with its proximal wall is configured such thatsaid proximal wall curves outward upon expansion of the occlusion deviceso as to come into position in such manner with the septal wall.
 8. Theocclusion device according to claim 1, wherein the distal retention areaexhibits a holder preferably arranged axially to crosspiece.
 9. Theocclusion device according to claim 8, wherein at least one connectingelement is further provided at distal retention area, wherein saidconnecting element is engageable with a catheter.
 10. The occlusiondevice according claim 1, wherein the occlusion device is configured tobe reversibly foldable and expandable such that the expanded occlusiondevice can be folded up using an explantation catheter, wherein theforce-fit connection between the proximal wall and the septal wall isdisengaged.
 11. A method of manufacturing an occlusion device, inparticular an occlusion device according to any one of the precedingclaims, wherein the method comprises the following procedural steps:forming a ball-shaped, bulb-shaped or teardrop-shaped hollow braiding bymeans of a braiding process known per se, wherein said hollow braidingis bundled at a first distal end and exhibits a completely closedproximal wall having a continuous surface on an opposite second proximalend; and forming a proximal retention area on the proximal wall, adistal retention area on the bundled first end, and a cylindricalcrosspiece arranged between said proximal and distal retention areas.12. The method according to claim 11 further comprising the proceduralstep of forming a holder on the bundled distal end of the hollowbraiding.
 13. The method according to claim 11, wherein the proceduralstep of forming the retention areas and the crosspiece includes moldingand/or heat treatment.